The present invention relates to a manually adjustable articulated positioning device having air driven clutch hinges between articulating members that may be used for adjusting and controlling the position of instruments held at the head-terminus end of such device. Such devices may be used, for example, in holding and positioning instruments and/or light sources used in medicine, dentistry, and other applications where adjustable positioning of such items is desired. The device according to the present invention allows for the instrument to be positioned in the elevation, extension, lateral position, orientation, and approach aspects relative to the fixed base of the device or the position of the target.
Various repositionable structures have been developed for making adjustments of tools, surgical instruments and the like. Typically, such structures have a plurality of articulated members or `arms` that are coupled through various rotating devices so as to be relatively movable by either sliding or rotating relative to a fixed base structure or to one another.
The typical form of a repositionable structure takes the form of articulating arm members being joined by a hinged joint capable of being fixed by some means. For example, Baitelle in U.S. Pat. 4,431,329 shows a typical hinge locking mechanism that operates by friction comprising axially butting plates attached to respective articulating arm members; a threaded tightening bolt with a lever handle is used to bring and hold these plates into frictional engagement with each other thereby holding the articulating arm members in a fixed position. Copeland et. al., in U.S. Pat. 5,683,064 show articulating members coupled by rotational couplings on two mutually perpendicular axes thereby forming universal joints with axially-facing rotational surfaces; the rotational engagement surfaces are designed to resist rotation when engaged by use of a line such as a cable which traverses the joints (running centrally through the joints) and normally applies tension via a spring, causing all the joints to lock and to hold the end platform at a given position and orientation. A manually operable control is normally provided to extend the length of the line and disengage all the joints simultaneously, whereupon the support platform can be moved freely to a new position anywhere in a three dimensional range, as well as tilted, etc. The control is released at the new position to again hold the platform in place. Other cable-controlled positioning units are described by Rello in U.S. Pat. No. 5,779,209, and by Copeland et. al., in U.S. Pat. No. 5,564,667.
There are several drawbacks to frictional locking hinges as described by Baitelle. For example, if two or more rotational joints each lock separately and independently of each other, moving the support platform to a new position is cumbersome; for a series of rotational joints between articulated members, unlocking, moving the support platform to a new position and relocking each successive joint is tedious and makes it difficult to obtain the desired exact location for the support platform. In addition, such frictional locking hinges have the undesired tendency to slip if the threaded bolts holding the two opposing friction faces becomes loosened through changes in air temperature or lack of sufficient tightening. Likewise, there are several drawbacks to cable locking hinges as described by Copeland et. al, and Rello. For example, with cable systems the operator must have sufficient hand strength to operate the release and locking mechanism used to work the cable, there is the issue of cable wear over time, the issue of providing strengthened pulley points whenever the cable needs to be directed in other than a 180 degree angle (i.e., around any turn), and the issue of reinforced cable attachment points that will not yield or break when tension is constantly applied each time the cable is locked under tension or released under little or no tension.
Accordingly, while adjustable articulated positioning devices such as the positionable lights used in dentist operatories are commercially available, the need still exists for positioning devices that can be locked into positions more securely than those available presently, do not have the problems associated with cable tension and wear, do not need additional strength built into the device at cable attachment points, and do not need to be dependent upon the finger or hand strength of the operator to function properly.